Japan's Defense Ministry will allow US military MV-22 Osprey flights to continue in the country, despite previously calling for them to be grounded after a fatal crash killed three marines. Tokyo says it accepts US assurances the flights are safe.

Defense Minister Itsunori Onodera had asked the US to temporarily stop flying the Osprey tilt-rotor aircraft in his country after a fatal crash off the coast of Australia on Saturday. The accident involved a US Marines aircraft stationed at an airbase in Japan.

However, the Japanese Defense Ministry softened its stance on Friday, issuing a statement which said the US military is "taking reasonable measures" and "the US force's explanation that it can conduct safe flights of MV-22 Ospreys is understandable."

"It is appropriate (for Japan) to demand flights with maximum consideration to safety," the statement reads, as quoted by AFP.

The statement comes just one day after the US Marine Corps said that "the Osprey is safe to fly."

According to a US official cited by AFP, the crash occurred after the Osprey clipped the back of the ‘USS Green Bay’ while trying to land on the amphibious transport ship.

The US military reportedly resumed operations of the aircraft in Okinawa just two days after the fatal crash, which the Marine Corps has referred to as a "mishap."

The resumption of flights outraged Deputy Okinawa Governor Moritake Tomikawa, who filed a protest with the US on Tuesday.

“It is impossible to overcome the utmost outrage concerning the conducted flight, despite our requests [to refrain from it],” he told the top commander of the US military in Okinawa, Lieutenant General Lawrence Nicholson, on Tuesday, Japan's NHK newspaper reported.

However, other reports said the US military did not lift the "operational pause" of flights until Wednesday.

The US military has 24 MV-22s stationed at Marine Corps Air Station Futenma in Ginowan, Okinawa Prefecture. Residents have long protested their deployment to the base, which is located in the middle of the densely populated city.

Other critics have slammed the Osprey - which takes off and lands like a helicopter but flies like an airplane - as being unsafe.

Locals in Okinawa became particularly concerned about the Osprey and other US aircraft in June, when an MV-22 had to make an emergency landing on the island on the same day as F/A-18 fighter jets.

In December, an MV-22 based at Futenma crash-landed off Okinawa's coast, injuring five crew members. That incident was also dubbed a "mishap" by the Pentagon.

Later that month, thousands of Okinawa residents staged a mass rally to protest the presence of American helipads and US forces on the island.

The Osprey - which has two engines positioned on fixed wingtips that allow it to land and take off vertically - has also been involved in a number of fatal incidents in the US, including a crash in Arizona in 2000 which killed 19 Marines.

However, the US Marine Corps says the Osprey is actually one of the safest in its air fleet, claiming problems that previously existed with the aircraft have been fixed.